1. Field of the Invention
The present invention relates to a device and method for modulating naturally occurring rhythmic body activity and more particularly to a closed-loop device and a method of utilizing musical pattern for inducing rhythms.
2. Discussion of Prior Art
Man and the higher animals respond, both psychologically and physiologically, to stimuli in the environment. Through its activating effect upon subcortical neuronal systems of the brain, sound modifies the brain's pacing of cardiovascular, endocrine, metabolic, reproductive and neurological functions.
The interaction between sound and motor activity of the body has been an acknowledged fact since the early days of human civilization. It was seen especially in the relation between dancing and music. However, the isolation of musical elements that most affect psychophysiological responses is not an easy task. It has been the subject of intensive research.
Regularly recurring sound is known to affect respiration rate and serves as a positive reinforcement of rhythmic movements, provided that respiration and movements are synchronized with the sound. An example of this is the effect of fast rhythmic drumming on the central nervous system; it affects brain wave frequencies, and leads to a state of trance.
Yet music is much more than rhythmic or non-rhythmic patterns of sound. That is why there has been much controversy about the quality and magnitude of the physical effects of music on motor responses. For example, in a variety of cultures it was believed that there exists a specific correspondence between heart rate and musical rhythm. However, scientific studies failed to confirm this hypothesis.
It has now been found that rhythmic cardiovascular activity of the body, including the pulse rate, the respiration rate and the periodic change in the diameter of small blood vessels associated with the activity of the symphathetic nervous system (the so-called "vasomotion"), as well as the brain waves respond most strongly to external stimuli with almost identical rhythm. A certain type of "resonance" phenomenon occurs when controlled musical patterns are induced in a body, causing shifts or changes in the natural body activity to a higher or lower activity or causing stabilization of the activity.
The rhythmic activities of a body are known to occur in frequency bands, which are usually non-overlapping. The electrical signal representing these activities presents instantaneous or average values. Examples of the frequency bands are as follows: Vasomotion frequency is smaller or equal to 0.1 Hz; respiration 0.15-0.4 Hz; heart beating 0.8-2 Hz; alpha, beta and theta brain wave frequencies are higher or comparable to 4 Hz. Some rhythms modulate others, e.g., respiration and vasomotion are expressed in the ECG signal by frequency modulation.